Informal Fallacies

Fallacies in General

All fallacies are non sequiturs. “Non sequitur” is latin for “it does not follow.” You don’t need to remember the many types of fallacies if you’re good at figuring out that a conclusion doesn’t follow from its premise(s). However, you may find it useful to think about the different types of fallacies.

Ad Hominem: Circumstantial

This version begins the same way as the ad hominem abusive, but instead of heaping verbal abuse on his or her opponent, the respondent attempts to discredit the opponent’s argument by alluding to certain circumstances that affect the opponent.*

Examples

“Stacey is only arguing in favor of minimum wage because, if the minimum wage is increased, then her own salary will go up. Obviously her arguments are worthless.”

“The congresswoman argues that we should open up the Arctic National Wildlife Refuge for oil drilling. But she just wants to reward her rich cronies in the oil industry who got her elected. Therefore, we can hardly take her arguments seriously.”

Does Al Gore invest in clean energy because he cares about the environment, or does he only claim to care about the environment so that he can make money off of clean energy investments? If he doesn’t really care, then, when he says that we should invest in solar energy over coal energy because it will make the air cleaner, he could just want to line his own pockets. (Gore’s motives have no bearing on whether using solar energy over coal energy results in cleaner air.)

Ad Hominem: You Too

(Tu Quoque)
The tu quoque (“you too”) fallacy begins the same way as the other two varieties of the ad hominem argument, except that the second arguer attempts to make the first appear to be hypocritical or arguing in bad faith.*

Examples

“Political operative Newt Gingrich has argued about the need to preserve family values. But who is he to talk? Gingrich has been married three times. He divorced his first wife while she was hospitalized for cancer, and he engaged in an extramarital affair while he was married to his second wife. Clearly, Gingrich’s arguments are trash.”*

“How can you possibly argue against smoking when you are a smoker yourself?”

Appeal to Force

(Argumentum ad Baculum)
This fallacy occurs whenever an arguer poses a conclusion to another person and tells that person either implicitly or explicitly that some harm will come to them if they do not accept the conclusion.*

“If we surrender, the enemy will take the chance to slaughter us all.”

Secretary to boss: “I deserve a raise in salary for the coming year. After all, you know how friendly I am with your wife, and I’m sure you wouldn’t want her to find out what’s been going on between you and that sexpot client of yours.”

“According to the theory of evolution, the best creatures will survive. Therefore, we shouldn’t make special efforts to feed the poor. If they don’t survive, that just means they weren’t as fit as we are.”*

“There have always been wars. That’s why we shouldn’t intervene in wars or try to reduce the number of wars. War is just a natural state.”*

Appeal to the People

(Argumentum ad Populum)
This fallacy uses the desires of people to be loved, esteemed, admired, valued, recognized, and accepted by others to get the reader or listener to accept a conclusion.*

Examples

Direct

“Ladies and gentlemen, today the lines of battle have been drawn. When the din of clashing armor has finally died away, the Freedom Party will emerge victorious! We are the true party of the American people! We embody the values that all real Americans hold sacred! We cherish and protect our founding fathers’ vision that gave birth to the Constitution! We stand for decency and righteousness, for self-determination and the liberty to conduct our affairs as each of us freely chooses! In the face of our standard bearing the American eagle of freedom, our muddle-headed, weak-kneed opponents with their collectivist mentalities and their deluded programs for social reform will buckle and collapse! Victory will be ours, so help us God!”

Indirect — Bandwagon

“Tens of millions of people voted for Caligula; therefore, Caligula will be a great leader.”

Indirect — Appeal to Vanity

“A beautiful, intelligent person like you will naturally see the correctness of my argument.”

Indirect — Appeal to Snobbery

Genetic Fallacy

This fallacy occurs when an arguer evaluates a thing in terms of its earlier context, ignoring relevant changes that may have altered its character in the interim and then uses that evaluation to support a conclusion in the present.*

Examples

“I will never get married. Did you know that the word ‘wife’ originally referred to those women who were captured, after the invasion and conquest of a neighboring tribe, and brought home to be slaves? Marriage was a degradation!”*

“The Freedom Party says that we need to keep women out of the workforce. The party has a long history of sexism, though, so we can just disregard this.”

“You apologize? Well, since the word ‘apology’ comes from the Greek word for ‘defense,’ I can only assume that you are trying to defend your despicable behavior.”*

“I will not vote for Schroeder. Everyone knows she is German, and we all know German history. No anti-Semitic candidates for me!”*

There is no way we should support eugenics! That idea was advocated by the Nazis in Hitler’s Germany, don’t forget!*

Misrepresentation

This fallacy is committed when an arguer distorts an opponent’s argument for the purpose of more easily attacking it, demolishes the distorted argument, and then concludes that the opponent’s real argument has been demolished.*

Examples

“Senator Barrow advocates increased Social Security benefits for the poor. It is regrettable that the senator finds it necessary to advocate socialism. Socialism defeats initiative, takes away promised rewards, and leads directly to inefficiency and big government. It was tried for years in Eastern Europe, and it failed miserably. Clearly, socialism is no good.”

Missing the Point

(Ignoratio Elenchi)
This fallacy occurs when the premises of an argument support one particular conclusion, but then a different conclusion, often vaguely related to the correct conclusion, is drawn.*

Examples

“Abuse of the welfare system is rampant nowadays. Our only alternative is to abolish the system altogether.”

“Mr. Rhodes is suffering from amnesia and has no recollection whatever of the events of the past two weeks. We can only conclude that he did not commit the crime of murdering his wife a week ago, as he has been accused of doing.”

Perfectionist

This fallacy is committed when one says that a proposal or claim should be rejected solely because it doesn’t solve the problem perfectly, in cases where perfection isn’t really required.*

Examples

“You said hiring a house cleaner would solve our cleaning problems because we both have full-time jobs. Now, look what happened: every week, after cleaning the toaster oven, our house cleaner leaves it unplugged. I should never have listened to you about hiring a house cleaner.”*

“What’s the point of campaigns against drunk driving? People are going to do it no matter what.”

Red Herring

The red herring fallacy is committed when the arguer diverts the attention of the reader or listener by changing the subject to a different but sometimes subtly related one.*

Examples

“You say that our animal shelter’s ad campaign is offensive, but you forget that our shelter has saved thousands of animals and has protected the health of the general public for decades.”*

“There is a good deal of talk these days about the need to eliminate pesticides from our fruits and vegetables. But many of these foods are essential to our health. Carrots are an excellent source of vitamin A, broccoli is rich in iron, and oranges and grapefruit have lots of vitamin C.”*

Relativist

This fallacy is committed when we assert that we all have our own reason for thinking and acting a certain way, which is valid in our realm but not necessarily to another person’s sphere. (If we believe that there are common objective truths that can be proved or disproved, relativism or subjectivism is a fallacy. If subjectivism is correct, the relativist fallacy is not fallacious.)*

Examples

“Well, I think human sacrifice is immoral, but the ancient Mayans didn’t, so it wasn’t wrong for them.”*

“In a democracy, every citizen has the right to vote. In my definition of democracy, the weight of a vote is proportional to the amount of property a citizen owns.”*Share

Wishful Thinking

This fallacy is committed when we believe something simply because we have a strong desire for something to be a certain way.*Examples

“My wife has been missing for more than 10 years, but I know that she’s still alive. She just couldn’t be dead.”*

“There’s a perfect partner out there for everyone in this world. Wanting that partner will lead us to that partner. Then, once we have them, as long as we want it to work badly enough, it will work.”*

Fallacies of Weak Induction

This fallacy occurs not because the premises are logically irrelevant to the conclusion, as is the case with fallacies of relevance, but because the connection between premises and conclusion is not strong enough to support the conclusion.*Share

Appeal to Ignorance

(Argumentum ad Ignorantiam)
This fallacy is committed when the premises of an argument state that nothing has been proved one way or the other about something, and the conclusion then makes a definite assertion about that thing.*

Examples

“There is no compelling evidence that UFOs are not visiting the Earth; therefore, UFOs are visiting Earth.” Or, conversely, “There is no compelling evidence that UFOs are visiting Earth; therefore, UFOs are not visiting Earth.”

“People have been trying for centuries to disprove the existence of unicorns, and no one has ever succeeded; therefore, we must conclude that unicorns do exist.”

Cherry-Picking

Cherry-picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position while ignoring a significant portion of related cases or data that may contradict that position.

Examples

“Buying the Apex 5000 computer for our company was the right thing to do. It meets our company’s needs; it runs the programs we want it to run; it will be delivered quickly; and it costs much less than what we had budgeted.” (The speaker has intentionally suppressed that these computers were purchased from her sister-in-law at a 30% higher price than they could have been purchased elsewhere. Also omitted was the fact that a recent unbiased analysis of 10 comparable computers placed the Apex 5000 near the bottom of the list in performance and usability.)*

“Look at what Giancarlo said the other day: ‘I … hate white people.’ How can anyone like someone who is so racist?” (While this quote from Giancarlo is technically correct, the word left out in the quote is “don’t.” So, the full quote is, “I don’t hate white people.” The speaker selected only certain words to create a desired impression.)

Hasty Generalization (Anecdote)

This fallacy occurs when there is a reasonable likelihood that the sample is not representative of the group. Such a likelihood may arise if the sample is either too small or not randomly selected.* Note: This fallacy is very similar to the fallacy of composition.

Examples

“Bernie Madoff was a crook; therefore, all financial managers are crooks.”

“It is wrong to kill; therefore, war can never be just because people are killed during war.”

“Several recent terrorist attacks have been carried out by radical Islamic groups. Therefore all Muslims are terrorists.”

“Yeah, I’ve read the health warnings on those cigarette packs and I know about all that health research, but my brother smokes, and he says he’s never been sick a day in his life, so I know smoking can’t really hurt you.”*

“I lived in Berlin for a year. While there, I noticed that many people walked dogs in the street and were always cursing at their dogs. That’s just how Berliners are.”

“José was talking to his Amish friend Moses the other day. Moses says that he never loans anyone money. Isn’t it funny how cheap Amish people are?”

Slippery Slope

This fallacy is a variety of the false cause fallacy. It occurs when the conclusion of an argument rests on an alleged chain reaction and there is not sufficient reason to think that the chain reaction will actually take place.*

Examples

“The legalization of drugs will eventually lead to the total collapse of civilization.”

“The legalization of prostitution will eventually lead to the total collapse of civilization.”

Weak Analogy

The fallacy of weak analogy is committed when the analogy is not strong enough to support the conclusion that is drawn.*

Examples

“Guns are like hammers—they’re both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous.”*

“People who have to have a cup of coffee every morning before they can function have no less a problem than alcoholics who have to have their alcohol each day to sustain them.”*

Fallacies of Presumption

These fallacies arise not because the premises are irrelevant to the conclusion or provide insufficient reason for believing the conclusion but because the premises presume what they purport to prove.*

Circular Reasoning

(petitio principii)
This fallacy is committed whenever the arguer creates the illusion that inadequate premises provide adequate support for the conclusion by leaving out a possibly false (shaky) key premise, by restating a possibly false premise as the conclusion, or by reasoning in a circle.*

False Dichotomy

This fallacy is committed when an either/or premise presents two unlikely alternatives as if they were the only ones available, and the arguer then eliminates the undesirable alternative, leaving the desirable one as the conclusion.*

Middle Ground

This fallacy, also called the Golden Mean or Appeal to Moderation, is committed when a position is made to appear as being between two extremes when one position is actually correct (or more probable) while the other is incorrect (or less probable).

Examples

“Holly said that vaccinations caused autism in children, but her scientifically well-read friend Caleb said that this claim had been debunked and proven false. Their friend Alice offered a compromise that vaccinations must cause some autism, just not all autism.”*

“Billie says that gays are dangerous and can’t be permitted to work in occupations where they come into contact with children. Ira says thay they’re no more dangerous than straight people. Spencer settles the dispute by saying that, clearly not all gays are dangerous. So, we will just keep them under strict supervision when they’re around children and let parents decide whether gays can be around their children.”*

Suppressed Evidence

This fallacy is committed when an inductive argument ignores some important piece of evidence.*

Examples

“Most dogs are friendly and pose no threat to people who pet them; therefore, it would be safe to pet the little dog that is approaching us now which is foaming at the mouth.”

“The Patriot missile is an excellent weapon. Tests show that in 98% of firings, the missile successfully left the launch pad.”
(This is technically true. However, this omits the fact that, after leaving the launch pad successfully, a majority of the missiles either blew up in mid-air or failed to hit the targets.)*

Amphibole

The fallacy of amphibole occurs when the arguer misinterprets an ambiguous statement and then draws a conclusion based on this faulty interpretation. Unlike equivocation, this fallacy hinges on grammar rather than definitions.*

Examples

“Don’t kill yourself; let the church help.” (Will the church help you kill yourself or help prevent you from killing yourself?)

“Her parents watered the flowers, yet they died.” (Did the parents die, or did the flowers die?)

“Professor Johnson said that he will give a lecture about heart failure in the biology lecture hall. It must be the case that a number of heart failures have occurred there recently.” (It’s unclear whether there have been a lot of heart failures in the biology lecture hall or if that’s where a lecture regarding heart failures will be held.)

Equivocation

The fallacy of equivocation occurs when the conclusion of an argument depends on the fact that a word or phrase is used, either explicitly or implicitly, in two different senses in the argument.*

Examples

“If we were going to push for an election, then we should have made sure that we did something to determine who was going to win.” (Because of different meanings of the word “determine,” it’s unclear if the speaker wanted to try to change the election’s outcome or simply to study the election process.)

“The laws imply lawgivers. There are laws in nature. Therefore, there must be a cosmic lawgiver.” (This train of thought, intentionally or unintentionally, confuses laws of nature like gravity with laws made by people like ones against smoking in a restaurant.)

Fallacies of Grammatical Analogy

Composition

The fallacy of composition is committed when the conclusion of an argument depends on the erroneous transference of an attribute from the parts of something onto the whole.* This fallacy is so similar to the hasty generalization that I’m not sure the distinction matters. If you want to explore the distinction more, I recommend this.

Examples

“My new car has a great engine; therefore, it’s a great car.”

“Each player on this basketball team is an excellent athlete; therefore, the team as a whole is excellent.”

Division

The fallacy is committed when the conclusion of an argument depends on the erroneous transference of an attribute from a whole (or a class) onto its parts (or members).* Note: This fallacy is similar to the fallacy of accident.

Examples

“Salt is a nonpoisonous compound; therefore, its component elements, sodium and chlorine, are nonpoisonous.”

“This airplane was made in Seattle; therefore, every component part of this airplane was made in Seattle.”

The average American family has 2.5 children. The Jones family is an average American family. Therefore, the Jones family has 2.5 children.”*